circuit boards on which electronic components are to be mounted have been known in the past. Such electronic components include semiconductor devices or capacitors etc. Such semiconductor devices include ICs (integrated circuits) or LSI (large scale integrated circuits) etc.
As such a circuit board, a board which has a resin layer (insulating layer) containing a resin and a conductive layer formed on the resin layer and containing a metal is known (for example, Patent Document 1: Japanese Patent Publication (A) No. 9-23065).
In order to increase a bonding strength between the resin layer and the conductive layer, the practice has been to roughen the surface of the resin layer. However, roughening is not preferred from the viewpoint of maintaining good electrical characteristics of the circuit board. In particular, when wiring lines formed by the conductive layer are miniaturized, the roughening has a larger effect causing a drop in electrical characteristics. Accordingly, increasing the bonding strength by a method other than roughening is desired.